Pesticidal compositions comprising phosphinothioyl disulfide



United States Patent PESTICIDAL COMPOSITIONS COMPRISING PHOSPHINOTHIOYL DISULFIDE Joe R. Willard, Middleport, N.Y., James Forrest Allen, South Charleston, W. Va., and Kenneth R. Holden, East Point, Ga., assignors to Food Machinery and Chemical Corporation, New York, N.Y., a corporation of Delaware N0 Drawing. Filed Aug. 18, 1955, Ser. No. 529,358

4 Claims. (Cl. 167-22) wherein R R R and K, may be any hydrocarbon or substituted hydrocarbon radicals and may be the same or different.

Methods for the preparation of those disulfides in which the KS are all the same are known to the art, but the preparation of mixed disulfides, i.e. those in which at least one of the R groups is dilferent from the others, has not previously been disclosed.

It is an object of this invention to provide a method for the preparation of phosphinothioyl disulfides having mixed alkoxy groups or aryloxy groups.

Another object of this invention is to provide new compositions of matter useful as pesticides.

Still another object of this invention is to provide an improved method for killing pests.

Other objects and advantages of this invention will become apparent in the course of the following detailed description and disclosure.

Phosphinothioyl disulfides in which one or more of the alkoxy groups or aryloxy groups are different from the others may be prepared according to the process of this invention in a two step reaction sequence described as follows:

(1) A mixture of alcohols and/or phenols is reacted with phosphorus pentasulfide to give a mixture of phosphorodithioates having the general formula:

65 (2) A phosphorodithioate or mixture of phosphorodithioates is oxidized to. give a phosphinothioyl disulfide 12,983,644 Patented May 9, 1961 ICC or a mixture of phosphinothioyl disulfides having the general formula:

\fi fi/ 5 /.PS-SP R OR, in which R R R and R may be any hydrocarbon or substituted hydrocarbon radicals.

Suitable oxidizing agents for this conversion are nitrous acid, nitric acid, chromic acid, oxides of nitrogen, such as are produced by the action of a strong mineral acid upon an alkali metal nitrite, hydrogen peroxide, chlorine, iodine, metallic persulfates, and the like.

To illustrate the preparation of a mixture of bis(dialkoxyphosphinothioyl) disulfides using the process of this invention, a mixture of ethanoland 2-propanol gives a mixture of three phosphorodithioates upon treatment with phosphorus pentasulfide, according to the following equatrons:

CHsCHzO S| CHaifHOH CHa' CHa

Upon oxidation with sodium nitrite and sulfuric acid these three phosphorodithioates would give a mixture of the following six disulfides:

CHsCHzO S S OCHtCHa sassy OCHzCHs ornomo onaonlo s s OCHiCHS CHsCHnO OHaCHiO fi s r-s-s-r o (iJHOHs CHa CHsCHzO OCHCH:

CHa

l CHaCHzO S S OCHCH: \II II/ This methodmay be used to produce mixtures of phosphinothioyl disulfides of varying compositions by varying the proportions of the alcohols or phenols used in the preparation of the phosphorodithioates or by varying the proportions of the phosphorodithioates used in the preparation of the disulfides.

In addition to bis(dialkoxyphosphinothioyl) disulfides, bis(diaryloxyphosphinothioyl) disulfides as well as compounds in which there are both alkoxy and aryloxy groups in the same molecule may be prepared by the method of this invention.

The phosphinothioyl disulfides having mixed R groups have been found to. display a pronounced increase in pesticidal activity over those compounds in which all the R groups are the same. The phosphinothioyl disulfides derived from the phosphorodithioates prepared from an equimolar mixture of ethanol and 2-propanol, for ex ample, displayed an activity against mites which was twice as great as the pesticidal activity of bis(diethoxyphosphinothioyl) disufide and at least twenty times as great as the activity of bis(di-2-propoxyphosphinothioyl) disulfide.

These compounds may be applied to plant foliage or to other surfaces infested by pests in the form of sprays, or as dust compositions, or as baits. An aqueous suspension of a wettable powder formulation of the disulfide or mixture of disulfides on an inert carrier has been found to be suitable in the spray technique. Carriers suitable for both spravs and dusts include attaclav. silica. kaolin clay, talc, calcium carbonate and similar inert diluents. It is generally found preferable to utilize highly absorbent diluents where diluent is to be used in spravs with high concentrations of up to about 25% of the disulfide whereas diluents of low absorbent power are satisfactory in the case of lower concentrations of disulfide.

i It is desirable to use wetting or emulsifying agents in the dispersions of the disulfides in order to obtain uniformity and stability of dispersion. The use of wetting agents also facilitates the application of the spray by increasing the spreading action of the composition, re sulting in better contact with the surface being treated, and consequently effecting better contact with the mites, aphids, or other pests.

Baits are preparedby mixing the phosphinothioyl disulfides with a suitable feed, such as a mixture of cornmeal and sugar.

The preparation and pesticidal activity of representative compounds is shown in the following examples, which are intended solely for purposes of illustration and are not to be construed as in any way limiting the scope of this invention.

Example 1 illustrates the preparation of hydrogen phosphorodithioates from mixtures of alcohols or phenols.

EXAMPLE 1. Preparation of hydrogen phosphorodithioates One molar quantity of phosphorus pentasulfide was placed in a ronndbottomed flask equipped with a reflux condenser and dropping funnel and surrounded by a water-bath and connected with an absorber for the evolved hydrogen sulfide. Two molar quantities of each of the alcohols or phenols used was added rapidly and aesaema 7 the initial vigorous exothermic reaction allowed to proceed at 40 C. until evolution of hydrogen sulfide had nearly ceased. The temperature of the water bath was then raised to boiling and heating continued until gas evolution again ceased. The liquid reaction mixture was filtered to remove traces of unreacted phosphorus pentasulfide. A list of the alcohols and phenols used and yields obtained is given in Table I. j

TABLE I.-HYDROGEN PHOSPHORODITHIOATES Alcohol or Alcohol or phenol Yield, Characteristics phenol Percent methanol- 1 l-propenol. 83 light green.

, Do .do 85 very pale green.

l-butanol 87 Do.

. 85 light green.

85 deep blue-brown. 69 colorless, viscous. allyl alcohol 86 viscous, colorless 2,2,2-trichloroethanoL- 83 dark rod-brown. 2-n1ethylpropanol-1.-.. 90 dark green-brown. Z-butanol 86 pale orange-brown. allyl alcohoL. 80 medium green-brown- 2-propauol. 96-98 pale green-brown. cyclohexan 92 pale yellow.

3-pentanol. 93 pale blue-gray.

3-heptano1 91 Do. 2 hexanol 92 medium blue-gray. 4-ch1or6pi1'61i61'I" 2-bu nol. 76 llght orangebrown. Z-chloroethan 88 viscous, colorless,

89 medium green-brown.

D 2-methylpropanol-l 90 dark blue-brown. Do 2-butanel 84 light orange-brown. Do. allyl alcohol" 91 dark green-brown Do. phenol Do 4-chlorophenol I Due to the tendency of 0,0-dlallylhydrogen phosphorodithioate to explode if overheated, the mixtures containing allyl alcohol were maintained at 65 as a maximum temperature rather than the usual boiling water temperature.

b Notisolated. I I v Traces of hydrogen chloride were'detected during the filtration of this add.

The following example illustrates the preparation of phosphinothioyl disulfides from various hydrogen phosphorodithioates prepared from the reaction of an equimolar mixture of alcohols or phenols with phosphorus pentasulfirle.

EXAMPLE 2.

Preparation of phosphinothioyl disulfides One molar equivalent of the appropriate hydrogen phosphorodithioate was suspended in approximately twice its volume of water and sufiicient 4 -5 molar aqueous sodium hydroxide slowly added to a pH 6.0-7.0. To the nearly neutral solution was added 1.1 molar equivalents of 5.5

molar aqueous sodium nitrite solution, traces of nitrogen oxide fumes being evolved during this addition. To the solution was then slowly added 2.2 molar equivalents of 2.2 molar aqueous sulfuric acid solution, the rate of addition being regulated soas to reduce foaming to a minimum. The mixture was stirred for a total of 45 ture of 50-60 under 1 -2 mm. A list of the alcohols andphenols used in the preparation of the phosphorodithioates and yieldsof the disulfides obtained is given in Table II.

3' TABLE n.-PHosPnINoTn1oYL n1shim Inns z P Analysis,

Alcohol or Alcohol or Yield Percent phenol phenol Percent Characteristics Calcd. Found methanol ethanol 84 colorless 18.0 17.0

Do 1-propanol 51 pale gre 2-propano1- 1-butano1 68 yellow 15. 5 15. 78 pale yellow- 15. 14. 8

green. 74 do 15. 5 15.3 80-90 yellow-grew 2-methylpro- 76 pale green..-.. 14. 5 14. 5

panol-l. 2-butanol 69 pale yellow 14. 5 14.4 allyl alcohol... 74 red-brown... tetrahydro- 57 viscous, yelturturyl low-orange.

D0 b 63 orange- Do b 55 orange-brown.

1- r0 anol-- 59 yellowgreemp D o 86 do 14.5 14. 7 2-propanol- 79 do.

Do 62 pale green.-

61 yellow-green- 71 viscous,

yellowbrown. b 27 deep oranae b 17 orangebrown.

I The product consisted of a liquid and a solid, the latter identified as bis(di-Z-propoxyphosphinothioyl) disulfide.

Yield calculated on basis 01 entered Piss.

- An alternative procedure for the preparation of the phosphinothioyl disulfides from the phosphorodithioates was accomplished as follows:

EXAMPLE 3 Two molar equivalents of the 0,0-dialkyl hydrogen phosphorodithioates was suspended in 1.1 molar equivalents of 2.2 molar sulfuric acid solution. To the well- Inerts usable in Formulation 1- would include Attaclay, silica, kaolin clay and other highly absorbent inerts. In Formulations 2 and 3, talc, calcium carbonate and similar inerts of low absorbent power would be usable. Wetting agents which have been found to be useful in formulations of this type include sodium lignosulfonates, sodium alkylnapthalene sulfonates, sodium sulfated fatty acid esters, sodium lauryl sulfate, and other wetting agents capable of lowering the surface tension of the solutions in which they are immersed.

The following example illustrates the pesticidal activities of various phosphinothioyl disulfides prepared from mixtures of alcohols or phenols.

EXAMPLE 5 The pesticide was applied to the foliage of bean plants in various concentrations in the form of an aqueous sus pension of a wettable powder formulation according to Example 4, using 25 parts of phosphinothioyl disulfide, 3 parts of sodium lignosulfonate and 72 parts of Attaclay. The plants were infested with two-spotted mites, T. bimaculatus, or pea aphids, M. pisi, and observations made at intervals of 3 to 6 days to determine the mortality counts of mites or aphids.

The mortality rates in the following table are those observed 3 days after use of a spray having a concentration of active ingredient of .1250 parts per million.

The LD value, which is a measure of the minimum efiective concentration of the compound being tested as a toxicant was obtained in the following manner. Decreasing amounts of toxicant were applied to test surfaces. A plot was made of the percent control versus the concentration of active material in parts per million. The LD value below is that concentration in parts per million at which the mortality rate is 50%.

TABLE IV.-PESTICIDAL ACTIVITIES 0F PHOSPHINO- THIOYL DISULFIDES DERIVED FROM MIXTURES OF ALCOHOLS OR PHENOLS stirred acid solution was slowly added 2.2 molar equiva- M I lents of 5.5 molar sodium nitrite solut1on. Stirring was Alcohol g gg continued for 24% hours from the time of the initial or phenol Alcohol or phenol addition. The mixture was treated 38 111 Example 2. Mites Aphids Mites Aphids The bis(dialkoxyphosphmothioyl) disulfides prepared are given in Table III, listed as the alcohols used in the ethanol 95 21 230 l-propanol- 95 preparation of the phosphorodithioates 2 propauolm 100 100 38 625 TABLE III l-b t n L.

2-butan0l 100 2-methylpropano 97 P Analysis, allyl alcohol 100 9 Yield Percent -Pmpanol 100 100 12 125 Alcohol Alcohol Percent Characteristics Z-methylpropanol 100 2-butanol- 100 Calcd. Found allylalcohol 100 cyclohexanol. 85 3-pentanol 99 156 methanol. allyl alcohol... 51 yellow-brown. 3-heptanol 43 Do 2,2,2-trichloro- 71 dark brown.-. 2-hpvmnl 91 ethanol. phenol 31 ethanol 2-propano1 80-90 yellow-green 4-chlorophenol- 33 Do cyclohexanoL. 79 viscous 2b 13 yellow- 2-chloroethann 100 156 green. Z-propanol 100 yellow-green 13.6 13.5 l-butanoL- 172 I 12.9 t 12.1 0 17 Do Z-chloroethan l 99 green, DO 131181101. 22 2-propanol 2-chloro- 83 pale green Do 4-chlorophenol 39 ethanol The following example illustrates several suitable formulationsfor use as pestlcldes, the quantmes of the The increased pesticidal activity of the phosphinothioyl 0.11s constituents being given imparts by weight.

disulfides having diiferent ester groups over those in which all the ester groups are the same is brought out by the following example.

EXAMPLE 6 The pesticidal activity of various bis(dialkoxyphosphinothioyl) disulfides was determined and compared to the activity of bis(diethoxyphosphinothioyl) disulfide and the ratio of the activity of the disulfide, X, to the activity of bis(diethoxyphosphinothioyl) disulfide recorded in Table V.

' TABLE v Activity Ratio Mites Aphids bis(diethoxyphosphinothioyl)disulfide 1.0 1.0 bis(di-Z-propoxyphosphinothioyl) disulfide 0. 1 0.1

bis(dialkoxyphosphinothloyl) disulfide derived from equimolar mixture of ethanol and 2-propanel 2.0 1.4 bis(dialkoxyphosphinothioyl) disulfide obtained by oxidation of an equimolar mixture of 0,0-diethyl and 0,0-di-2-propyl hydrogen phosphorodithinato 1,0 1,4

The effect upon the pesticidal activity of the bis(dialkoxyphosphinothioyl) disulfides produced by varying the ratios of the alcohols used in their preparation is indicated by the following example.

EXAMPLE 7 p The disulfide derived from ethyl alcohol and 2-propyl alcohol was prepared using the ratios of the alcohols shown in Table VI. The pesticidal activity of the compounds thus prepared was compared to the activity of the disulfide prepared from an equimolar mixture of ethyl alcohol and 2-propyl alcohol and the ratio of the pesticidal activity of these compounds to the pesticidal activity of the 1:1 compound recorded in Table VI.

The foregoing examples illustrate several modes of carrying out this invention, but are not intended to be exhaustive of the possibilities which may occur to those skilled in the art. Disulfides having a greater variety of alkoxy or phenoxy groups than those indicated in the examples,'for instance, may be used without departing from thescope of this invention.

Pursuant to the requirements of the patent statutes, the principle of this invention has been explained and exemplified in a manner so that it can be readily practiced by those skilled in the art, such exemplification including what is considered to represent the best embodiment of the invention. However, it should be clearly understood that, within'the scope of the appended claims, the invention may be practiced by those skilled in the art, and having the benefit of this disclosure, otherwise than as specifically described and exemplified herein.

7 That which is claimed as patentably novel is;

1. The phosphinothioyl disulfide composition of the f mu 1. 1 1 V R s s \ll Il/ PSSP where R R R and R are selected from the group consisting of ethyl and isopropyl radicals, produced by reacting phosphorus pentasulfide with the mixture of ethanol and isopropanol wherein said alcohols are present in the ratio of three moles of ethanol per mole of isopropanol to form a mixture of hydrogen phosphorodithioates, and oxidizing said -mixture of phosphorodithioates to produce said phosphinothioyl disulfide composition.

2. Thephosphinothioyl disulfide composition of the formula 1 1 1 'RiO s s 'ORL whereinRi, R5, R and R are selected from the group consisting of ethyl and isopropyl radicals, produced by reactingphosphorus pentasulfide with the mixture of ethanol'and isopropanol wherein said alcohols are present in the ratio of three of six moles of ethanol per mole of isopropanol to form a mixture of hydrogen phosphorodithioates, 'and oxidizing said mixture of phosphorodithioates to'produce said phosphinothioyl disulfide composition. 1

3. The method of controlling mite pests which comprisesapplying to the infested area a toxic amount and concentration of a phosphinothioyl disulfide of the formula I p 1150 0 Rs wherein R R R and R are selected from the group consisting of ethyl and isopropyl radicals, said composition produced by reacting phosphorus pentasulfide with the 'mixture of ethanol and isopropanol wherein said alcohols are present in the ratio of three moles of ethanol per mole of isopropanol to form a mixture of hydrogen phosphorodithioates, and oxidizing said mixture of phosphorodithioates to produce saidphosphinothioyl disulfide composition.

' 4. The method of controlling mite pests which comprises applying to the infested area a toxic amount and concentration of a phosphinothioyl disulfide composition of the formula References Cited in the file of this patent UNITED STATES PATENTS 1,763,851 Johnson June 17, 1930 1,763,852 Johnson June 17, 1930 2,060,815 MacAfee Nov;'17, 1936 2,471,115 Mikeska May 24, 1949 2,523,147 Dean et al. Sept. 19, 1950 2,526,497,: Mikeska Oct. 17, 1950 2,705,694 Bartlett Apr.'5, 1955 2,798,880 Williams .et al. July 9, 1957 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION atent No. 2,983,644 May 9 1961 Joe R. Willard et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 8, line 17 for "of six moles" read to six holes Signed and sealed this 3rd day of October 1961.

Z SEAL) Ittest:

ERNEST W. SWIDER DAVID L. LADD Xttesting Officer Commissioner of Patents USCOMM-DC 

3. THE METHOD OF CONTROLLING MITE PESTS WHICH COMPRISES APPLYING TO THE INFESTED AREA A TOXIC AMOUNT AND CONCENTRATION OF A PHOSPHINOTHIOYL DISULFIDE OF THE FORMULA 